No abstract

M-OMS-2 materials (M = K+, Cu2+, Co2+) were prepared by an uncomplicated reflux method, and the cryptomelane crystalline structure was confirmed by X-ray diffraction patterns. Element analysis recorded ~56 - ~59 wt.% of Mn in the three synthesized samples and ~2.8 wt.% loadings of dopants over Co-OMS-2 and Cu-OMS-2 materials. A titration method valued the average oxidation states of manganese at 3.60, 3.71 and 3.77 for K-OMS-2, Co-OMS-2 and Cu-OMS-2, respectively. In comparison with K-OMS-2, Co and Cu dopants depicted a significant enhancement catalytic activity in removal of formaldehyde at low (5%) and high (65 %) relative humidity (RH). Cu-OMS-2 showed the highest catalyst performance with ~90 % of formaldehyde conversion at 150 °C, 65% RH, whereas only ~40 % (for Co-OMS-2) and ~26 % (for K-OMS-2) of that were observed. The finding results promised a potential Cu-OMS-2 material for designed low-costly catalyst in formaldehyde removal at a wide range of RH.

Nowadays, steel bridge structure is becoming the trend of highways and bridges construction industry on not only the material characteristic but also its ability to be manufactured easily and reduce the constructing time. However, this structure still has its own disadvantages. One of the most critical factors greatly influencing the performance of the whole structure is the buckling capacity of the main girders, especially during construction stage. The most common solution for increasing the structure’s buckling capacity is to provide it with discrete bracing along the girder’s length. The designing of bracing for steel bridges requires high precision. If the design of the system is much stiffer than it demands, the structure will easily be prone to fatigue problems. In the other hand, if the bracing design does not meet its required stiffness, the whole structure’s stability will greatly reduce. Presently, many projects are designed too sufficiently leading to a huge waste of cost and time. Therefore, the expected results of this study are to propose an optimal design process for the bracing system design of steel I girder simple span bridges and a finite element model of a real-life steel bridge to confirm the reliability of the specification proposed.